I think the real issue is being touched on but not exactly hit dead center. It's less about the need for multiple competitive services (Good!) and more about the possible balkanization as each publisher becomes a self-contained store (Bad!). I think it's awful that in the future I'd have to have an individual customer account and resident "minder" masquerading as a download service for each publisher. This eliminates the pleasantness and convenience of being able to go to one source (my choice of source).

Analogy: You buy your food not from a supermarket or even a farmer's market, but have a standing contract from each food maker. So for your bread, meat, vegetables, sauces, dairy, and other things you must have a relationship and keep track of each supplier, something that the store used to do for you, making it more convenient.

2nd analogy: You watch movies at the theaters own by their respective makers. So you go to the Disney theater, the Sony theater, and so on rather than have most or all your shows in one convenient place.

3rd analogy: You buy your books from each publisher, not a central shop like Amazon or Barnes and Noble (or some European equivalent).

The supermarket/retailer concept is something that exists for a reason: it provides a real service and convenience to the customer for a price. Sometimes that price is passed to the customer; sometimes that price is passed to the manufacturer.